SF Bay Region Atmospheric Mercury Monitoring Funded by

SF Bay Region Atmospheric Mercury Monitoring Funded by: RMP, USEPA w/ services by: NADP/MDN, Contra Costa, San Francisco, San Jose

Relevant Management Questions • Are current estimates about loading to San Francisco Bay from watersheds, wastewater treatment facilities, and atmosphere valid? • What is the contribution of atmospheric deposition to urban storm water?

SF Region Atmospheric Hg • RMP Pilot Study – 1999 -2000, wet deposition + dry ambient concentration, 3 sites • Mercury Deposition Network (MDN) – wet deposition continued 2000 -2006 @ RMP pilot study South Bay site (NASA Ames) • Guadalupe & NASA Ambient Hg – ambient concentration @NASA, Calero, Fall 2005

RMP Pilot Study Sites • Away from sources as practicable • Located North (Martinez), Central (Treasure Island), South (NASA Ames) Bay • NASA Ames becomes MDN site

NASA Ames • MDN CA 72 “San Jose” site

Calero Reservoir

RMP Pilot Study/MDN • Aerochem (wet deposition) collector

Guadalupe/NASA Ambient • EPA Region IX Mobile Hg Lab

Mobile Hg Lab (Interior) • Tekran automated Hg analyzer w/ particulate and reactive speciation modules. – 2537 – 1135 – 1130

2006 California MDN Sites San Jose Sequoia NP

Results: RMP Pilot Study • Wet deposition & rainfall concentrations South Bay Central Bay North Bay Region Area (km 2) 485 214 434 1133 Rainfall (cm/yr) 36 68 58 53 Hg Conc (ng/L) 9. 7 6. 6 7. 4 8. 0 Wet Dep (µg/m 2·yr) 3. 5 4. 3 4. 2 Loading (kg/yr) 1. 7 0. 96 1. 8 4. 8

Results: MDN 2 nd half 2003 San Jose Sequoia 2. 04 µg/m 2. 115 m precip 17. 7 ng/L 2. 56 µg/m 2. 526 m precip 4. 87 ng/L (3. 60 µg/m 2 13. 4 ng/L all year) 2004 2. 02 µg/m 2. 257 m precip 7. 88 ng/L 1. 74 µg/m 2. 412 m precip 4. 22 ng/L 2005 3. 56 µg/m 2. 431 m precip 8. 26 ng/L 6. 42 µg/m 2 1. 29 m precip 4. 98 ng/L • RMP Pilot S Bay: Conc < 10 ng/L, rainfall <. 5 m/yr

Results: RMP Pilot Study • Atmospheric Concentrations (pg/m 3) Average Stdev South Bay Central Bay North Bay Entire Estuary 2. 20 1. 90 2. 30 2. 10 . 66 . 33 . 59 . 57 • No speciation measured

Results: Calero • Daily afternoon Hg max (all species) • Reactive + particulate ~0. 3% of elemental

Results: NASA • Daily morning Hg (elemental) max • Reactive + particulate ~0. 2% of elemental

Summary: • Atmospheric conc and annual wet dep similar to previous RMP Pilot Study (Bayside & watershed sites similar magnitude) • Direct wet dep flux to Bay ~4 µg/m 2·yr (load ~5 kg/yr) • Reactive + particulate ~0. 2 -0. 3% of elemental Hg (~20 x lower than previous RMP Pilot Study estimate of ~5% from literature) • Direct dry dep flux to Bay ~2. 5 µg/m 2·yr (~3 kg/yr load, w/ 2 kg elemental, 1 kg reactive+particulate)

Management Implications: (with a bit of handwaving) • Reactive+particulate= ionic dry dep ~ 1 kg/yr • Ionic wet dep unknown, possibly ~. 015 kg/yr (0. 3% of total) to 5 kg/yr (100%) • New ionic mercury most readily available for methylation (METAALICUS, 6% of applied 202 Hg(II) converted to Me 202 Hg within 1 day) • 0. 4 to 2 pg/L·day ionic Hg available from air dep for methylation (1% to 5% of ambient Me. Hg conc) • Need speciation for wet dep and other Hg loads to the Bay (which <1% of tot Hg becomes Me. Hg? )